Fixed oxide fuel cells are known which are constructed to provide desired outputs by means of a stack of a multiplicity of fuel cells. In each of the fuel cells, separators are provided on the opposite surfaces of a membrane electrode assembly (also referred to as “MEA”), i.e. sandwich the membrane electrode assembly, via current collectors. With the current collectors interposed between the separators and the MEA, it is possible to secure given contact areas between the MEA and the separators while allowing manufacturing errors of the MEA and separators.
In each of the separators are formed gas flow paths (or gas passages) for directing fuel gas and oxidant gas to the MEA, and opening portions for directing fuel gas and oxidant gas to the gas flow paths. With a multiplicity of the fuel cells (i.e., separators) stacked together, the opening portions of the individual separators are positioned or aligned coaxially to form or constitute manifolds. Thus, fuel gas and oxidant gas can be supplied to the manifolds and then directed to the MEAs via the gas flow paths of the separators.
In order to form the manifolds by stacking a multiplicity of the separators, there is a need to seal between the stacked separators (i.e., jointed portions or joints of the manifolds) by means of seal portions so that the fuel gas and oxidant gas can be prevented from flowing out through the joints of the manifolds. Japanese Patent Application Laid-Open Publication No. 2004-39573 (hereinafter referred to as “relevant patent literature”), for example, discloses a fuel cell which seals between the stacked separators (joints of the manifolds) by means of seal portions made of glass.
In the fuel cell disclosed in the relevant patent literature, the glass-made seal portions seal between the stacked separators (joints of the manifolds). Therefore, when the fixed oxide fuel cell has varied relatively greatly in temperature, for example, it is difficult for the glass-made seal portions to follow the relatively great variation. As a consequence, the glass-made seal portions might be damaged due to the relatively great variation of the fuel cell, so that the fuel gas and oxidant gas might undesirably flow out from the manifolds.